^41:3.6 ¶ Not all stars are solid, but many of the older ones are. Some of the reddish, faintly glimmering stars have acquired a density at the centre of their enormous masses which would be expressed by saying that 1 cm³ of such a star, if on Urantia, would weigh 166 kg. The enormous pressure, accompanied by loss of heat and circulating energy, has resulted in bringing the orbits of the basic material units closer and closer together until they now closely approach the status of electronic condensation. This process of cooling and contraction may continue to the limiting and critical explosion point of ultimatonic condensation.

^41:3.7 Most of the giant suns are relatively young; most of the dwarf stars are old, but not all. The collisional dwarfs may be very young and may glow with an intense white light, never having known an initial red stage of youthful shining. Both very young and very old suns usually shine with a reddish glow. The yellow tinge indicates moderate youth or approaching old age, but the brilliant white light signifies robust and extended adult life.

^41:3.8 ¶ While all adolescent suns do not pass through a pulsating stage, at least not visibly, when looking out into space you may observe many of these younger stars whose gigantic respiratory heaves require from 2 to 7 days to complete a cycle. Your own sun still carries a diminishing legacy of the mighty upswellings of its younger days, but the period has lengthened from the former 3.5 day pulsations to the present 11.5 year sunspot cycles.

^41:3.9 Stellar variables have numerous origins. In some double stars the tides caused by rapidly changing distances as the two bodies swing around their orbits also occasion periodic fluctuations of light. These gravity variations produce regular and recurrent flares, just as the capture of meteors by the accretion of energy-material at the surface would result in a comparatively sudden flash of light which would speedily recede to normal brightness for that sun. Sometimes a sun will capture a stream of meteors in a line of lessened gravity opposition, and occasionally collisions cause stellar flare-ups, but the majority of such phenomena are wholly due to internal fluctuations.

^41:3.10 In one group of variable stars the period of light fluctuation is directly dependent on luminosity, and knowledge of this fact enables astronomers to utilize such suns as universe lighthouses or accurate measuring points for the further exploration of distant star clusters. By this technique it is possible to measure stellar distances most precisely up to more than 1,000,000 light-years. Better methods of space measurement and improved telescopic technique will sometime more fully disclose the 10 grand divisions of the superuniverse of Orvonton; you will at least recognize 8 of these immense sectors as enormous and fairly symmetrical star clusters.

4. SUN DENSITY

^41:4.1 The mass of your sun is slightly greater than the estimate of your physicists, who have reckoned it as about 2·10³⁰ kg[1]. It now exists about halfway between the most dense and the most diffuse stars, having about 1.5 times the density of water. But your sun is neither a liquid nor a solid — it is gaseous — and this is true notwithstanding the difficulty of explaining how gaseous matter can attain this and even much greater densities.

^41:4.2 ¶ Gaseous, liquid, and solid states are matters of atomic-molecular relationships, but density is a relationship of space and mass. Density varies directly with the quantity of mass in space and inversely with the amount of space in mass, the space between the central cores of matter and the particles which whirl around these centres as well as the space within such material particles.

^41:4.3 ¶ Cooling stars can be physically gaseous and tremendously dense at the same time. You are not familiar with the solar supergases, but these and other unusual forms of matter explain how even nonsolid suns can attain a density equal to iron — about the same as Urantia — and yet be in a highly heated gaseous state and continue to function as suns. The atoms in these dense supergases are exceptionally small; they contain few electrons. Such suns have also largely lost their free ultimatonic stores of energy.

^41:4.4 One of your near-by suns, which started life with about the same mass as yours, has now contracted almost to the size of Urantia, having become 40,000 times[2] as dense as your sun. The density of this hot-cold gaseous-solid is about 61 kg/cm³. And still this sun shines with a faint reddish glow, the senile glimmer of a dying monarch of light.

^41:4.5 Most of the suns, however, are not so dense. One of your nearer neighbours has a density exactly equal to that of your atmosphere at sea level. If you were in the interior of this sun, you would be unable to discern anything. And temperature permitting, you could penetrate the majority of the suns which twinkle in the night sky and notice no more matter than you perceive in the air of your earthly living rooms.

^41:4.6 The massive sun of Veluntia, one of the largest in Orvonton, has a density only 0.001 that of Urantia’s atmosphere. Were it in composition similar to your atmosphere and not superheated, it would be such a vacuum that human beings would speedily suffocate if they were in or on it.

^41:4.7 Another of the Orvonton giants now has a surface temperature a trifle under 1,600 degrees. Its diameter is over 482,803,200 km — ample room to accommodate your sun and the present orbit of the earth. And yet, for all this enormous size, over 40,000,000 times that of your sun, its mass is only about 30 times greater. These enormous suns have an extending fringe that reaches almost from one to the other.

5. SOLAR RADIATION

^41:5.1 That the suns of space are not very dense is proved by the steady streams of escaping light-energies. Too great a density would retain light by opacity until the light-energy pressure reached the explosion point. There is a tremendous light or gas pressure within a sun to cause it to shoot forth such a stream of energy as to penetrate space for millions upon millions of kilometres to energize, light, and heat the distant planets. 4.6 m of surface of the density of Urantia would effectually prevent the escape of all X rays and light-energies from a sun until the rising internal pressure of accumulating energies resulting from atomic dismemberment overcame gravity with a tremendous outward explosion.

^41:5.2 Light, in the presence of the propulsive gases, is highly explosive when confined at high temperatures by opaque retaining walls. Light is real. As you value energy and power on your world, sunlight would be economical at a million pounds sterling a kilogram.

^41:5.3 The interior of your sun is a vast X-ray generator. The suns are supported from within by the incessant bombardment of these mighty emanations.

^41:5.4 It requires more than 500,000 years for an X-ray-stimulated electron to work its way from the very centre of an average sun up to the solar surface, whence it starts out on its space adventure, maybe to warm an inhabited planet, to be captured by a meteor, to participate in the birth of an atom, to be attracted by a highly charged dark island of space, or to find its space flight terminated by a final plunge into the surface of a sun similar to the one of its origin.

^41:5.5 The X rays of a sun’s interior charge the highly heated and agitated electrons with sufficient energy to carry them out through space, past the hosts of detaining influences of intervening matter and, in spite of divergent gravity attractions, on to the distant spheres of the remote systems. The great energy of velocity required to escape the gravity clutch of a sun is sufficient to ensure that the sunbeam will travel on with unabated velocity until it encounters considerable masses of matter; whereupon it is quickly transformed into heat with the liberation of other energies.